(a) (i) Testis: to produce male gametes.
(ii) Scrotum: to provide optimal temperature to testis for the formation of sperm.
(iii) vas deferens: to deliver the sperms to the urinary bladder.
(iv) prostrate glands: to secrete the fluid which provides nutrition and medium for transport of sperms.
(b) Testosterone has following roles:
(i) regulates formation of sperms.
(ii) brings about the changes in boys during adolescence.